A vehicle seat is described in Japanese Patent No. 4763275. In the vehicle seat of Japanese Patent No. 4763275, as shown in FIG. 9, a rear part 103b of an elastic body 103 configuring a seat cushion 101 and a rotation-center-side end part 106c of an elastic body 106 configuring a seat back 105 are in contact with each other through covers (not shown). Thus, when the seat back 105 is rotated with respect to the seat cushion 101, a friction force F is generated due to the rubbing of a cover of the seat cushion 101 side with a cover of the seat back 105 side. Here, the friction force F is expressed by the product of a load P at which the cover of the seat back 105 side pushes the cover of the seat cushion 101 side and the coefficient of friction μ between the covers.
In order to improve the holding property of a seated person in the vehicle seat, generally, side parts of both sides of the seat cushion 101 are formed from an elastic body harder than that of a central seating part. In addition, the side parts on both sides of the seat back 105 are formed from an elastic body harder than that of a central backrest part. Thus, at the contact portion of the seat cushion 101 and the seat back 105, the relatively hard elastic bodies are brought into surface contact with each other through the covers at the positions of the left and right side parts. Accordingly, the load P at which the cover of the seat back 105 presses the cover of the seat cushion 101 at the positions of the left and right side parts of the contact portion increases. As a result, the friction force between the seat cushion 101 and the seat back 105 increases, and when the seat back 105 is rotated with respect to the seat cushion 101, the resistance increases.